Steel is the foundation of the state industry. Ladle is an important equipment for the storage, transportation, and refining of molten steel. Almost all new steel types are developed through secondary refining in ladle. Refractory is not only lining material, but also reactive in the metallurgical process, so it is one of the important sources of non-metallic inclusions and harmful elements in the steel, and also the main channel for energy consumption in the iron and steel smelting process. Therefore, refractory has become a key link in the modern steel smelting process.
At present, the destruction of the refractory is mainly manifested as slag corrosion damage, and there are more factors that affect the slag corrosion damage of the ladle refractory in comparison with other refractories. In theory, once contacted with the refractory, the slag will firstly penetrate the refractory through the pores of the refractory having a large specific surface area and a small pore size, where oversaturation (threshold value) is easily reached for forming new compounds. As more high-melting compounds are formed by reaction, the adhesion of the compound will increase the surface roughness of the refractory and intensify the penetration, which in turn results in more high-melting compounds to be formed, then a cycle is formed, and finally the boundary layer between the refractory and the slag is thickened; as less high-melting compounds are formed by reaction, that is, more low-melting compounds are formed, then the surface roughness is reduced and the penetration is weakened, and if the slag is flowing at this time, then the slag cannot always reach the oversaturation, as a result of which, the refractory will continue to dissolve into the slag, which results in aggravating the damage to the refractory. A large number of studies have shown that during the service of alumina-magnesia spinel materials, the spinel captures FeO, MnO of the slag, the corundum absorbs CaO of the slag to form a dense layer of calcium hexaaluminate (abbreviated as CA6) on its surface, and viscosity of the slag increases due to the relative increase of SiO2 content. Therefore, the slag penetration resistance and the corrosion resistance of the refractory are enhanced. Zhang Dianjun etc. have studied the erosion behavior of corundum-spinel castables under the condition of refining slags with two different basicity. The results showed that the corrosion of castables under the condition of high basicity slag was slight, and that the penetrate reaction layer of castables under the condition of low basic slag is thicker. It shows that there is a big difference of slag resistance of inner lining material under different smelting conditions such as slag systems, slag compositions and steel types. Especially for lightweight refractory, the process of slag erosion is more complex due to lower bulk density, more pores, and more slag diffusion channels. It is required that the lightweight refractory has more micro-closed pores and the ability to form a slag-resistant protective layer under the condition of a wide range of slag composition, however the lightweight refractory currently reported is still difficult to meet the requirements. Therefore, it is of important practical significance and application value to develop a lightweight refractory with strong slag-resistance in order to reduce the refractory consumption of ladle, save energy, improve metallurgical production efficiency and steel quality.